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81.
Meriem Senissar Agnès Le Saux Na?ma Belgareh-Touzé Céline Adam Josette Banroques N. Kyle Tanner 《Nucleic acids research》2014,42(15):10005-10022
The DEAD-box helicase Ded1 is an essential yeast protein that is closely related to mammalian DDX3 and to other DEAD-box proteins involved in developmental and cell cycle regulation. Ded1 is considered to be a translation-initiation factor that helps the 40S ribosome scan the mRNA from the 5′ 7-methylguanosine cap to the AUG start codon. We used IgG pull-down experiments, mass spectrometry analyses, genetic experiments, sucrose gradients, in situ localizations and enzymatic assays to show that Ded1 is a cap-associated protein that actively shuttles between the cytoplasm and the nucleus. NanoLC-MS/MS analyses of purified complexes show that Ded1 is present in both nuclear and cytoplasmic mRNPs. Ded1 physically interacts with purified components of the nuclear CBC and the cytoplasmic eIF4F complexes, and its enzymatic activity is stimulated by these factors. In addition, we show that Ded1 is genetically linked to these factors. Ded1 comigrates with these proteins on sucrose gradients, but treatment with rapamycin does not appreciably alter the distribution of Ded1; thus, most of the Ded1 is in stable mRNP complexes. We conclude that Ded1 is an mRNP cofactor of the cap complex that may function to remodel the different mRNPs and thereby regulate the expression of the mRNAs. 相似文献
82.
Interplay of Optical,Morphological, and Electronic Effects of ZnO Optical Spacers in Highly Efficient Polymer Solar Cells
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Sadok Ben Dkhil David Duché Meriem Gaceur Anil K. Thakur Fatima Bencheikh Aboura Ludovic Escoubas Jean‐Jacques Simon Antonio Guerrero Juan Bisquert Germà Garcia‐Belmonte Qinye Bao Mats Fahlman Christine Videlot‐Ackermann Olivier Margeat Jörg Ackermann 《Liver Transplantation》2014,4(18)
Optical spacers based on metal oxide layers have been intensively studied in poly(3‐hexylthiophene) (P3HT) based polymer solar cells for optimizing light distribution inside the device, but to date, the potential of such a metal oxide spacer to improve the electronic performance of the polymer solar cells simultaneously has not yet be investigated. Here, a detailed study of performance improvement in high efficient polymer solar cells by insertion of solution‐processed ZnO optical spacer using ethanolamine surface modification is reported. Insertion of the modified ZnO optical spacer strongly improves the performance of polymer solar cells even in the absence of an increase in light absorption. The electric improvements of the device are related to improved electron extraction, reduced contact barrier, and reduced recombination at the cathode. Importantly, it is shown for the first time that the morphology of optical spacer layer is a crucial parameter to obtain highly efficient solar cells in normal device structures. By optimizing optical spacer effects, contact resistance, and morphology of ZnO optical spacers, poly[[4,8‐bis[(2‐ethylhexyl)oxy]benzo[1,2‐b:4,5‐b′]dithiophene‐2,6diyl] [3‐fluoro‐2‐[(2‐ethylhexyl)carbonyl] thieno[3,4‐b]thiophenediyl]] (PTB7):[6,6]‐phenyl‐C71‐butyric acid (PC70BM) bulk heterojunction solar cells with conversion efficiency of 7.6% are obtained in normal device structures with all‐solution‐processed interlayers. 相似文献
83.
Aureococcus anophagefferens is a picoplanktonic microalga that is very well adapted to growth at low nutrient and low light levels, causing devastating blooms ("brown tides") in estuarine waters. To study the factors involved in long-term acclimation to different light intensities, cells were acclimated for a number of generations to growth under low light (20μmolphotonsm(-2)s(-1)), medium light (60 or 90μmolphotonsm(-2)s(-1)) and high light (200μmolphotonsm(-2)s(-1)), and were analyzed for their contents of xanthophyll cycle carotenoids (the D pool), fucoxanthin and its derivatives (the F pool), Chls c(2) and c(3), and fucoxanthin Chl a/c polypeptides (FCPs). Higher growth light intensities resulted in increased steady state levels of both diadinoxanthin and diatoxanthin. However, it also resulted in the conversion of a significant fraction of fucoxanthin to 19'-butanoyloxyfucoxanthin without a change in the total F pool. The increase in 19'-butanoyloxyfucoxanthin was paralleled by a decrease in the effective antenna size, determined from the slope of the change in F(0) as a function of increasing light intensity. Transfer of acclimated cultures to a higher light intensity showed that the conversion of fucoxanthin to its derivative was a relatively slow process (time-frame of hours). We suggest the replacement of fucoxanthin with the bulkier 19'-butanoyloxyfucoxanthin results in a decrease in the light-harvesting efficiency of the FCP antenna and is part of the long-term acclimative response to growth at higher light intensities. 相似文献
84.
Manu Vanaerschot Ilse Maes Meriem Ouakad Vanessa Adaui Louis Maes Simonne De Doncker Suman Rijal Fran?ois Chappuis Jean-Claude Dujardin Saskia Decuypere 《PloS one》2010,5(8)
Background
Leishmania donovani is an intracellular protozoan parasite that causes a lethal systemic disease, visceral leishmaniasis (VL), and is transmitted between mammalian hosts by phlebotomine sandflies. Leishmania expertly survives in these ‘hostile’ environments with a unique redox system protecting against oxidative damage, and host manipulation skills suppressing oxidative outbursts of the mammalian host. Treating patients imposes an additional stress on the parasite and sodium stibogluconate (SSG) was used for over 70 years in the Indian subcontinent.Methodology/Principal Findings
We evaluated whether the survival capacity of clinical L. donovani isolates varies significantly at different stages of their life cycle by comparing proliferation, oxidative stress tolerance and infection capacity of 3 Nepalese L. donovani strains in several in vitro and in vivo models. In general, the two strains that were resistant to SSG, a stress encountered in patients, attained stationary phase at a higher parasite density, contained a higher amount of metacyclic parasites and had a greater capacity to cause in vivo infection in mice compared to the SSG-sensitive strain.Conclusions/Significance
The 2 SSG-resistant strains had superior survival skills as promastigotes and as amastigotes compared to the SSG-sensitive strain. These results could indicate that Leishmania parasites adapting successfully to antimonial drug pressure acquire an overall increased fitness, which stands in contrast to what is found for other organisms, where drug resistance is usually linked to a fitness cost. Further validation experiments are under way to verify this hypothesis. 相似文献85.
Attia Hana Finocchi Federica Orciani Monia Mehdi Meriem Zidi Jrah Ines Lazzarini Raffaella Balercia Giancarlo Mattioli Belmonte Monica 《Molecular biology reports》2021,48(8):5935-5942
Molecular Biology Reports - Male infertility is a problem that affects 10–15% of men of reproductive age. In particular, gametogenesis is a complex process in which inflammation may play a... 相似文献
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87.
A. Al‐Marzouqi S. Ben Meriem H. Al‐Waili S. Al‐Habsi 《Zeitschrift fur angewandte Ichthyologie》2011,27(3):820-826
Management of fish resources in the Western Indian Ocean is complicated due to the lack of data on the basic biology and landing statistics for exploited fish species. In this paper, a database including biological parameters, length frequency distributions and catches of Epinephelus gabriellae in Oman according to fleet components has been established to develop a management plan for its sustainable exploitation. Length cohort analyses and yield per recruit were examined by simulating changes in fishing effort in length at first capture and by introducing a seasonal ban for trawlers. The results showed a high sensitivity to the applied value of natural mortality (M). (i) With M = 0.40, a healthy status of the stock is observed; however, with M values of 0.20 and 0.15 the stock appears slightly overexploited, and actual F exceeds 10 and 30% of the F01 level, respectively. (ii) A moderate increase of length at first capture would not significantly affect the long‐term yield or stock spawning biomass; however, a substantial length increase would in the long‐term lead to a decrease in yields for the artisanal fleet using traps. (iii) A seasonal ban regulation for trawlers would not have a significant effect on the sustainable yield, but if the fishing effort were to increase considerably, a significant long‐term gain in yield would be obtained with a closed season from April‐September. 相似文献
88.
Calame M Cachafeiro M Philippe S Schouwey K Tekaya M Wanner D Sarkis C Kostic C Arsenijevic Y 《PloS one》2011,6(8):e23782
In normal mice, the lentiviral vector (LV) is very efficient to target the RPE cells, but transduces retinal neurons well only during development. In the present study, the tropism of LV has been investigated in the degenerating retina of mice, knowing that the retina structure changes during degeneration. We postulated that the viral transduction would be increased by the alteration of the outer limiting membrane (OLM). Two different LV pseudotypes were tested using the VSVG and the Mokola envelopes, as well as two animal models of retinal degeneration: light-damaged Balb-C and Rhodopsin knockout (Rho-/-) mice. After light damage, the OLM is altered and no significant increase of the number of transduced photoreceptors can be obtained with a LV-VSVG-Rhop-GFP vector. In the Rho-/- mice, an alteration of the OLM was also observed, but the possibility of transducing photoreceptors was decreased, probably by ongoing gliosis. The use of a ubiquitous promoter allows better photoreceptor transduction, suggesting that photoreceptor-specific promoter activity changes during late stages of photoreceptor degeneration. However, the number of targeted photoreceptors remains low. In contrast, LV pseudotyped with the Mokola envelope allows a wide dispersion of the vector into the retina (corresponding to the injection bleb) with preferential targeting of Müller cells, a situation which does not occur in the wild-type retina. Mokola-pseudotyped lentiviral vectors may serve to engineer these glial cells to deliver secreted therapeutic factors to a diseased area of the retina. 相似文献
89.
Background
Membrane proteins (MPs) play key roles in signal transduction. However, understanding their function at a molecular level is mostly hampered by the lack of protein in suitable amount and quality. Despite impressive developments in the expression of prokaryotic MPs, eukaryotic MP production has lagged behind and there is a need for new expression strategies. In a pilot study, we produced a Drosophila glutamate receptor specifically in the eyes of transgenic flies, exploiting the naturally abundant membrane stacks in the photoreceptor cells (PRCs). Now we address the question whether the PRCs also process different classes of medically relevant target MPs which were so far notoriously difficult to handle with conventional expression strategies.Principal Findings
We describe the homologous and heterologous expression of 10 different targets from the three major MP classes - G protein-coupled receptors (GPCRs), transporters and channels in Drosophila eyes. PRCs offered an extraordinary capacity to produce, fold and accommodate massive amounts of MPs. The expression of some MPs reached similar levels as the endogenous rhodopsin, indicating that the PRC membranes were almost unsaturable. Expression of endogenous rhodopsin was not affected by the target MPs and both could coexist in the membrane stacks. Heterologous expression levels reached about 270 to 500 pmol/mg total MP, resulting in 0.2–0.4 mg purified target MP from 1 g of fly heads. The metabotropic glutamate receptor and human serotonin transporter - both involved in synaptic transmission - showed native pharmacological characteristics and could be purified to homogeneity as a prerequisite for further studies.Significance
We demonstrate expression in Drosophila PRCs as an efficient and inexpensive tool for the large scale production of functional eukaryotic MPs. The fly eye system offers a number of advantages over conventional expression systems and paves the way for in-depth analyses of eukaryotic MPs that have so far not been accessible to biochemical and biophysical studies. 相似文献90.